'75 85HP gear lube pic/question

[Blue Bomb]

This is my first boat. I bought it this fall and I've had it out 5-6 times before the cold took over. I've fogged and stabil - ized it, Now I'm changin the lube. I'm storing it in my garage which is heated and stays between 40-50F. I drained the gear lube and it looked green. I suspect the milky green-ness indicates water getting in.

My question is, how bad is this. Do I need to re-seal the lower unit, or is this level of frothing OK.

I wish is was May.

Tom

 

[bgbass.1]

Re: '75 85HP gear lube pic/question

Looks like water inthere try changing the gaskets on the drain plugs probably getting in there at least a good place to start

 

[tashasdaddy]

Re: '75 85HP gear lube pic/question

i agree the drain and vent washers/seals, need to be changed every time the screw is removed. #1 reason for water intrusion. do this, then recheck after several runs. then if milky, time to rebuild lower unit.

 

[Blue Bomb]

Re: '75 85HP gear lube pic/question

Thanks guys, this place is great.

 

[ddennis]

Re: '75 85HP gear lube pic/question

Can't get better help than the guys here! Welcome to Iboats!

 

[Lakester]

Re: '75 85HP gear lube pic/question

hello,

YES, iboats IS great!! i am on a number of other lists... and its always one thing or another... unrelated posts to flames. here, it is business. and everyone is respectful and quite polite. iboats is a pleasure to contribute to, as well as, seek help and advice. the advice is accurate and beneficial, not to mention helpful.

t'sdaddy sed:

"then recheck after several runs. then if milky, time to rebuild lower unit.

how would u go about a rebuild to cure such a problem? where would the water come into the oil if not the drain plug washers? would it be thru the inner gaskets between the sections?

i still do not know how my 71 85HP lower unit seals to the exh hsg? . i see a gasket in my oem service manual, i have heard rubber O-ring, and i have read, but not sure about... use BRP sealer on the l/u to exh hsg when it is reassembled. i suppose i will 'see' when i drop it, but am still wondering... just what does seal it?

i read my oem service manual on how the Tstat sys works. i could see the parts, but was not sure of the full theory. then thru reading a couple of posts, and with that info on it, some more study, i garnished a complete working knowledge of its theory as it is applied to its parts and how it all works. then with add'l look see, i could see the water comes down from the heads, over to Tstat... out or redirects to pump, and out Tstat to down tubes to exit or water pump and back up to block. well, that is how i understand it currently.

regards,

lakester

 

[HighTrim]

Re: '75 85HP gear lube pic/question

If the drain and vent screw gaskets do not cure the problem, you will need to pressure test it, or just do a complete seal job.

To pressure/vacuum test a lower unit:

a) drain the gear oil
b) use an appropriate adapter with a gauge tee'd in to apply pressure or vacuum. No more than 15 psig for pressure. You can use a bicycle pump or any other compressed air source for pressure. For vacuum, you need a vacuum pump.
c) LU should retain some pressure or vacuum for 45 minutes minimum.
d) If pressure doesn't hold, submerge LU in water to find leak source [possibilities: drive shaft seal, prop shaft seal(s) (usually two), shift shaft seal and the fill/drain screw washers.]
e) replace offending seal(s) as required.


Lakester, some guys add the Scotchguard 845, which supercedes type M, on metal to metal contacts, such as the lu to exhaust housing as you describe, and some dont. THere is no gasket per se there. Even a little water leakage there is quite normal, as the cooling water is spent at that point anyways.